Attention is directed to an article by the inventors herein and their colleagues entitled "Electrical Properties of Ion-Implanted Poly (P-Phenylene Sulfide)" in the Proceedings of the Materials Research Society Conference (Boston, 1982) and a thesis of one of the inventors, J. S. Abel, of the same title (MIT 1982); both the article and thesis are incorporated herein by reference.
Conductive polymers are highly sought after at the present time to serve as substitutes for metallic and semiconductive materials in a variety of applications conducting electricity. For example, conductive polymers hold promise in batteries, solar cells, integrated circuits and electromagnetic shielding.
Considerable work has been done on a class of rigid backboned polymers that can be chemically doped (i.e. oxidized or reduced by a diffused chemical) and thus rendered conductive. Such polymers for example, include polyacetylene, and the dopants include iodine, arsenic pentafluoride or other similar materials having high electron affinity. Conductivities as high as 1000 (ohm cm).sup.-1 have been achieved but problems are encountered which presently preclude commercialization. Typically, the chemical doping treatment which renders the polymer conductive also renders it brittle and intractable. Moreover, the conductive derivatives are unstable under ambient conditions.
Irradiation of polymers has been practiced in the past for reasons unrelated to conductivity efforts. Various U.S. patents and publications have disclosed the use of electron bombardment to cross-link polymers and cure plastics. For example, see Timmerman, U.S. Pat. No. 3,142,629 and Smith, "Radiation Processing of Plastics", Modern Plastics Encyclopedia (1965). See also Weber, "A New Method for the Chemical Modifications of Polymers" 1981 Journal Chemical Society Communications, p.p. 522-523, wherein halogen ion implanation of polyacetylene is reported to produce color changes and improve stability.
Ionic radiation has also been used in the past on inorganic semiconductors and insulators. Implantation of ions to modify the conductivity of materials such as glasses and metal oxides is taught by Kurtin, U.S. Pat. No. 4,088,799, issued May 9, 1978.
There exists a need for stable conductive polymers which can be produced and processed easily. For complicated integrated circuit applications and the like, there also exists a need for methods and apparatus which can lay down precise conductive paths with carefully controlled conductivity.